With the development of mobile broadband, bandwidth requirements of end users are increasing. An existing networking manner in which a macro base station is used as a main part, however, cannot meet a bit rate required by a mobile broadband service.
To further improve system capacity, more low-power access points or small-cell base stations (collectively called small-cell base station below), for example, access points (access point) such as a home base station (Home eNodeB), a microbase station (micro eNodeB), a pico base station (pico eNodeB), a relay base station (Relay eNodeB), a femto base station (femto eNodeB), and a remote radio head (RRH, Remote Radio Head) in a Long Term Evolution (Long Term Evolution, LTE) technology, may be introduced in a range of the macro base station.
Transmit power of a small-cell base station is lower than transmit power of a macro base station, and downlink coverage of a small-cell base station is far less than downlink coverage of a macro base station. A hybrid networking manner with a macro base station and a small-cell base station can enhance coverage of a hot spot area, coverage of an indoor blind spot (or weak spot), and cell edge coverage of the macro base station, improve average cell throughput, cell edge throughput, and an uplink/downlink spectrum utilization rate of a cell, and reduce network costs and CAPEX (capital expenditure) of an operator, and the like. We call it a heterogeneous network.
When moving in a heterogeneous network in which a small-cell base station and a macro base station use an intra-frequency networking manner, a user equipment (UE) may pass through the small-cell base station. When passing through a border of the small-cell base station and the macro base station, the UE needs to perform a switchover. It is found out through studies that during a switchover on a heterogeneous network, a switchover failure rate of a UE is relatively high due to an interference cause. For example, resulting from downlink interference of a macro cell on a small cell, a failure occurs due to that a UE served by the small cell is difficult to receive downlink information; or for another example, when a UE served by a macro cell moves to a central area position of a small cell, resulting from downlink interference of the small cell on the macro cell, a failure occurs due to that the UE served by the macro cell is difficult to receive downlink information; for still another example, resulting from uplink interference of a UE served by a small cell on a UE served by a macro cell, a failure occurs due to that the macro cell cannot receive uplink information of the UE served by the macro cell.
If there are more small-cell base stations in a heterogeneous network, a UE needs to perform a switchover more frequently, and frequent switchover brings a large number of signaling and processing loads to the network. If the UE is not allowed to perform a switchover, so as to reduce the number of switchover times, the UE drops a call due to an interference problem. For example, if no switchover is performed when a UE served by a macro cell passes through a small cell, downlink of the small cell brings about strong downlink interference on the UE when the UE enters a center of the small cell, which causes the UE to drop a call.